Still sounds like water damage, whether the indicator shows it or not. Were your friend's phones more protected than yours? Were they BBs?

You can try the cleaning trick and see if that does anything.

Turn the device off. Press and roll the ball first in the direction that it doesn't work then roll it in all directions for at least a minute. Then press the ball again and blow some "canned" air all around it and roll for another 30 seconds or so. Release and turn the device back on.